Flowers on the Wall
by OptimisticLady
Summary: High School AU. Friendships are always formed in the weirdest of situations. Sherlock is more of an observer, Katrina is more of a participant. Combining the two was never a good idea - even if it did happen accidentally. Sherlock/OC.
1. Prologue

"So... Katrina – have you thought about what you'd like to do for your GCSEs?" asked Mrs Morgan, her form teacher. The fourteen year old girl then folded her arms across her chest and sat in thought for a few moments.

"I only want to do the _one_ English GCSE," she said. Mrs Morgan frowned.

"I know you sometimes struggle with the subject, but considering the fact I teach you English, I feel that you really could–"

"No thanks," Katrina interrupted. Her teacher sighed, running a hand through her blonde locks and scribbled down the route of English the girl would be taking on the piece of paper.

"Maths is compulsory." She carried on writing. "And science. Double or triple?"

"Triple," Katrina said adamantly. "It'll help more with Maths."

"All right... um, short course or full course Religious Education?"

"If I'm being made to take it I might as well do the full course. _And_ before _anything_ else is said, I am dropping Latin and carrying on with Italian."

"You could carry on with Latin if you _wanted_ to..."

"No way." She shook her head. "I'm so fed up with it. I hate the fact that this place makes us take it from year seven until _now._"

Mrs Morgan sighed again. Katrina could be very difficult and stubborn at the best of times, and it would get on the end of everyone's nerves by halfway through the year.

"Which humanity – or humanities – do you want to do?"

"Geography and Classical Civilisation."

"You want to do Classics but not Latin?"

"Don't judge me, Mrs Morgan." Katrina glared at the woman, and the front row of the form chuckled as they overhead that comment between the general chatter of the room. The girl smirked upon making her classmates laugh.

"Final subject?"

"Additional Maths."

"All right then..." Mrs Morgan finished off writing down Katrina's choices and handed her the form. "Get your parents to sign this and bring it back as soon as you can."

"Okay." Katrina folded the form and stood up, beginning to make her way to the back of the room where she had a tendency to sit, when her teacher called out for the next student she was going to talk to – and that student was Sherlock Holmes. Frowning, Katrina turned back. "What really bothers me, is that you're not exactly doing this in alphabetical order."

"Katrina, go and stand outside."

"Third time this week..." she murmured, and then said a little louder: "You're losing your touch, Mrs Morgan."

"Outside. _Now._"

Katrina rolled her eyes and carried on walking to the back, hastily putting the form in her bag before making her way out of the classroom. Upon getting out there, she peered in through the window and managed to catch her friend Irene's eye, and stuck out her tongue at her. Then she proceeded to catch Sherlock's eye and wave at him. The boy merely raised his eyebrows and tried to withhold a smirk to no avail, and Mrs Morgan turned around only to get up very angrily and hurry to the classroom door.

The girl stepped back and gave Mrs Morgan the most innocent of smiles as she came out into the corridor.

"What?" she asked her teacher, still grinning. "Not my fault Sherlock happened to look at the door and I happened to be looking _into_ the classroom."

"Katrina, I know it's getting to the end of the year, but you're going to have to really buck up for GCSEs. If you keep being disruptive and keep back chatting then you're not going to do well, are you?" Mrs Morgan replied, raising an eyebrow.

"Yet I'm doing pretty well anyway..."

Mrs Morgan couldn't argue with that.

"Come back inside in ten minutes."

With that, the teacher walked back into the classroom, slamming the door as she went.

Katrina rolled her eyes once more.


	2. What Makes It Fun

Year ten at secondary school. Katrina thought that her first day back after the summer was actually pretty good. They got their timetables, had that ridiculously long "welcome back to hell" assembly and they only had two lessons that day after lunch. Those two lessons for her were Maths, and then her Additional Maths class. It still surprised her that she could take that for GCSE. To most people, that amount of Maths would be _terrifying_, but it pleased Katrina to no end. It also meant that her Additional Maths class was _very_ small. It only had three people in it, and those people were herself, Sherlock Holmes and some other scrawny kid called Stephen.

None of them talked to each other unless it was _absolutely_ necessary. They preferred to just get on with it, really. This was Maths for those who took it seriously. Even better was the fact they had the _best_ Maths teacher in school, meaning that they wouldn't ever get stuck or feel like they weren't learning everything – it was great.

The only difficulties Katrina found in her other classes was that she wasn't with her friends in any of them. Of course, when with her friends she would mess about a _lot_, so she supposed being separated from them a large majority of the time wasn't such a bad thing. There were always break times and lunch times when she could see them. Weekends too. Holidays. So it really wasn't all _that_ bad in retrospect.

So the term wore on, and everyone was still finding it difficult to adjust to their new timetables, and the fact that all they learnt now would go towards some very important exams at the end of the two years didn't help stress levels. Nor did it help that year elevens kept constantly telling them that they had it easy. Surely they had gone through the same thing before? Surely they were told those exact words by their predecessors? And yet they still went on at the poor year tens who couldn't help being what they were – year tens.

At least there was one year eleven that was kind. Katrina had known him since halfway through year nine, when he told some of the other kids to stop picking on her for being good at maths – or some ridiculous reason that the people in her year felt it was okay to poke fun at her, and John Watson had swooped in to the save the day. Sometimes, when he wasn't with his year eleven friends, Katrina would sit with him. Especially when she fancied being around someone who was really quite sweet and a lot more mature than her friends. So what if he was only one year older than her? He had a high level of maturity that she wanted to achieve, except at the moment it was damn near impossible...

"How's Physics coming along?" he asked her once Wednesday lunchtime. They were sitting in the school canteen at a table right in the back corner where they knew nobody would disturb them. Katrina merely shrugged.

"Could be going better than it is. Maybe I shouldn't have taken all three sciences..." She picked up a cherry from her lunchbox and popped it in her mouth.

"You could always get someone to mentor you?"

She chewed on the cherry before delicately spitting out the pip into her hand and swallowing the fruit.

"Like who? You can't. You don't even do Physics..."

"One of the sixth formers could do–"

"No." She glared at him. "I have authority issues. You're really the only elder I actually respect."

John chuckled at that as he took a bite out of his sandwich. Katrina then sighed as her elbow rested on the table with her hand supporting her chin.

"Physics is boring. We're doing electricity at the moment, and I just want to get onto the good stuff like nuclear fusion, astrophysics and magnets!"

"You like the idea of learning about magnets but not electricity?" A slightly sharper voice came from the end of the table. Katrina and John both looked towards the source to see Sherlock sitting there, picking the canteen lunch he had bought in some variant of distaste. "Electricity has to be done before going into magnets – electromagnets, y'know?" He looked at Katrina curiously. "You're in my form."

"Oh, no shit, Sherlock. I've been in your form since we started here." Katrina rolled her eyes at him, and he huffed.

"Making an observation." It honestly looked like he was about to pout, or sulk while he ate his lunch.

"A really obvious observation," Katrina muttered as she put the lid back on her lunchbox, not feeling particularly hungry anymore. She could feel the scowl that was threatening to cut through her back as she turned from Sherlock to get off the bench and stand up. "I'm going to go outside for a bit."

"It's not that warm..." John raised an eyebrow at her in question. "It's quite cold for a September day."

"Cold, you say?"

"Yes."

"Fab. Matches my soul."

And off she went, Sherlock now staring at her in amusement rather than annoyance. However he _did_ become annoyed again, as he shuffled up the bench to sit opposite John.

"I didn't know you two were in the same form," the older boy commented.

"I didn't know you two were _friends._ I thought _I_ was your year ten friend."

"You are." John grinned at him. "But so is Katrina."

"She's very disruptive."

"Why do you think she likes to hang around with me then?"

Sherlock was silent for a moment.

"Maturity levels?"

"Yep."

"Interesting."

The continued to eat lunch in silence. Usually they would have kept talking, but they both kept on pondering over the somewhat fickle nature of Katrina. She liked to cause mischief, but she wanted to be an adult. They both supposed – but never said – it could work hand in hand. She was perfectly clever and could calm down when she needed to. She always did, anyway.

* * *

Usually, Chemistry was fun. Usually, when it was first thing on a Friday morning, the teacher was always late. Usually, that would cause general chit chat among the class, but this Friday morning was different. One of the students was up to something. This student had arrived in the lab five minutes early and had taken one of the plastic buckets from the cupboard, turning it upside down to write a word on it. Then, turning it the right way back up, they had filled it with water. Upon waiting for the rest of the class to come in – bar one particular student, who always strolled into Chemistry on a Friday morning a little bit late – before closing the door enough so that they could balance the bucket of water on top of it.

Cue intense laughter and shocked faces as the recipient of the prank open the door and had a bucket of water tip down onto their head, the word _FREAK_ written across the bucket for all to see. Sherlock lifted the bucket from his head and tossed it aside before running from the classroom, almost knocking over the teacher in the process.

Jim Moriarty received a detention when Greg Lestrade and Katrina Jenkins told her what had happened. Greg pitied Sherlock. Katrina was wondering what she could personally do to get back at Jim for being an almighty prat. While most of the class still sniggered over the ridiculous and mean idea of a prank, Katrina took whatever opportunity she could to shout obscenities at Jim and managed to get herself sent out of the classroom three times within the lesson. Almost got herself sent out a fourth, but then she apologised – a wound to her pride. Jim gave her a shark grin from across the room.

Sherlock wasn't a bad kid in the slightest. He just saw things differently to everyone else and his level of intelligence proved that he should be in a better school than the one he was at. It was hardly fair for him to be labelled something so cruel.

* * *

He didn't show up to lessons, and there were murmurs in the hallway between teachers that Katrina passed while travelling to her fourth lesson before lunch about the incident in the morning. Some of them in took the opportunity to glare at her – surely those obscenities that had come out of her mouth should never come from a fourteen year old girl's mouth! Not that she even cared.

But around lunchtime, she caught him at his locker and went to approach him, stopping in her tracks when she saw Jim there. And that was when a severe amount of courage built up inside of her for her to carry on walking over there.

"...Didn't you like it?" the Irish boy taunted the curly-haired one.

"_So_ hilarious..."

Ah. Apparently he did get sarcasm.

"Jim, why don't you just piss off and find a patch of soil to grow some potatoes to aid the famine of creativity in your brain?" Katrina asked him vehemently.

"That's just _rude,_" he replied. "And slightly racist."

"You're being rude to someone who doesn't deserve it."

"Katrina, go away!" Sherlock hissed at her. She gave him a _look_ and he didn't say another word.

"Back off of Curly and we're all good."

"Just playing a little game with him, is all." Jim reached up and ruffled up Sherlock's hair, causing the boy to flinch away and go to stand behind Katrina. "You're getting a _girl_ to fight your–"

_Smack!_

"Let's go, Curly Holmes," Katrina muttered, turning round and grabbing Sherlock's hand before pulling him down the corridor at a run, leaving Jim Moriarty clutching his bleeding nose by the lockers. Neither of them even dared to glance back as Katrina led him out of the school building, across the courtyard, through the changing rooms and out again, only to enter the small P.E equipment building on the edge of the field.

Letting go of his hand, Katrina flipped on the light switch and they managed to find a spot on the concrete floor of the little building – well, more like _massive shed_ – and settled there. They were silent for quite some time before even talking.

"I... I don't have lunch. I usually get it from the canteen..." Sherlock mumbled as he crossed his legs. Katrina pulled her food out of her bag.

"Here. You can share mine." She unwrapped a cheese and tomato sandwich, giving one half of it to Sherlock before setting out her fruit (cherries, as always), her packet of crisps and a chocolate bar in front of them.

"Wa' punchin' him really nec'ssary?" Sherlock asked her through a mouthful of food. He swallowed. "You'll get into trouble."

"When don't I?"

"I thought you wanted to be a grown up."

"That'll take a bit more time. Give me until my fifteenth birthday and I'll get back to you on that one. I don't care if they suspend me for a day for punching Jim."

"Why did you do it?"

"What he did in Chemistry wasn't necessary. It was mean. You... you know the bucket had 'freak' written on it?"

"Did it? Oh. Well... that's fairly normal."

"It shouldn't be..."

They fell into silence once more, and Sherlock picked up a couple of cherries.

"Funny... we've been in the same form since year seven, and yet we never really spoke to each other until now."

"We have a lot of classes together." Katrina shrugged. "And I just punched a guy for you."

Sherlock laughed a little.

"True. You did... thanks."

"You're welcome."

"Katrina... how badly do you want help with Physics?"

"More than you can imagine..."

"Do you want me to help you?"

Her eyes lit up and Sherlock smirked, taking that as a yes.

"I feel like GCSEs are going to be _much_ more fun," he concluded.

* * *

**A proper start to the story. I've got this one all mapped out and for once, there isn't really that much angst!**

**-OL**


End file.
